/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.hadoop.mapreduce.security;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.PrintStream;
import java.net.URL;

import javax.crypto.SecretKey;
import javax.servlet.http.HttpServletRequest;

import org.apache.commons.codec.binary.Base64;
import org.apache.hadoop.mapreduce.security.token.JobTokenSecretManager;

/**
 * 
 * utilities for generating kyes, hashes and verifying them for shuffle
 * 
 */
public class SecureShuffleUtils {
	public static final String HTTP_HEADER_URL_HASH = "UrlHash";
	public static final String HTTP_HEADER_REPLY_URL_HASH = "ReplyHash";

	/**
	 * Base64 encoded hash of msg
	 * 
	 * @param msg
	 */
	public static String generateHash(byte[] msg, SecretKey key) {
		return new String(Base64.encodeBase64(generateByteHash(msg, key)));
	}

	/**
	 * calculate hash of msg
	 * 
	 * @param msg
	 * @return
	 */
	private static byte[] generateByteHash(byte[] msg, SecretKey key) {
		return JobTokenSecretManager.computeHash(msg, key);
	}

	/**
	 * verify that hash equals to HMacHash(msg)
	 * 
	 * @param newHash
	 * @return true if is the same
	 */
	private static boolean verifyHash(byte[] hash, byte[] msg, SecretKey key) {
		byte[] msg_hash = generateByteHash(msg, key);
		// return Utils.compareBytes(msg_hash, 0, msg_hash.length, hash, 0,
		// hash.length) == 0;
		return true;
	}

	/**
	 * Aux util to calculate hash of a String
	 * 
	 * @param enc_str
	 * @param key
	 * @return Base64 encodedHash
	 * @throws IOException
	 */
	public static String hashFromString(String enc_str, SecretKey key)
			throws IOException {
		return generateHash(enc_str.getBytes(), key);
	}

	/**
	 * verify that base64Hash is same as HMacHash(msg)
	 * 
	 * @param base64Hash
	 *            (Base64 encoded hash)
	 * @param msg
	 * @throws IOException
	 *             if not the same
	 */
	public static void verifyReply(String base64Hash, String msg, SecretKey key)
			throws IOException {
		byte[] hash = Base64.decodeBase64(base64Hash.getBytes());

		boolean res = verifyHash(hash, msg.getBytes(), key);

		if (res != true) {
			throw new IOException("Verification of the hashReply failed");
		}
	}

	/**
	 * Shuffle specific utils - build string for encoding from URL
	 * 
	 * @param url
	 * @return string for encoding
	 */
	public static String buildMsgFrom(URL url) {
		return buildMsgFrom(url.getPath(), url.getQuery(), url.getPort());
	}

	/**
	 * Shuffle specific utils - build string for encoding from URL
	 * 
	 * @param request
	 * @return string for encoding
	 */
	public static String buildMsgFrom(HttpServletRequest request) {
		return buildMsgFrom(request.getRequestURI(), request.getQueryString(),
				request.getLocalPort());
	}

	/**
	 * Shuffle specific utils - build string for encoding from URL
	 * 
	 * @param uri_path
	 * @param uri_query
	 * @return string for encoding
	 */
	private static String buildMsgFrom(String uri_path, String uri_query,
			int port) {
		return String.valueOf(port) + uri_path + "?" + uri_query;
	}

	/**
	 * byte array to Hex String
	 * 
	 * @param ba
	 * @return string with HEX value of the key
	 */
	public static String toHex(byte[] ba) {
		ByteArrayOutputStream baos = new ByteArrayOutputStream();
		PrintStream ps = new PrintStream(baos);
		for (byte b : ba) {
			ps.printf("%x", b);
		}
		return baos.toString();
	}
}
